John, i had no intention to doubt drivers skills. Surely he was an experienced tanker, Bovington personnel are among most skillful professionals in their alley.
I myself have had a clutch failure driving a T-34. The release bearing failed causing gear jamming. Since the mainclutch was out, i stopped the tank by pulling back steering levers that open differential clutches and connect brakes. The controls in T-54 / 55 are basically identical with T-34, although a bit more sophisticated. So, it just seems unbelievable, that all those controls, mainclutch, differential clutch, steering brakes and fuelpump offswitchlever linkage, failed at same time. All those controls are operated independently with eachother.
So once more, no disrespect towards the driver, i hope this incident didn't cause him to give up his passion towards tanks. And bottom line, he DID stop the tank and no one got hurt.